heredity/mendelian genitics

Question 1

How is metaphase I of meiosis different from metaphase of mitosis?

Answer 1

In metaphase I of meiosis, homologous chromosome pairs (tetrads) line up together at the cell’s equator. In metaphase of mitosis, individual chromosomes (sister chromatids) line up single file.

Question 2

What are the stages of meiosis?

Answer 2

• Prophase I
• Metaphase I
• Anaphase I
• Telophase + cytokinesis

Question 3

What are homologous chromosomes?

Answer 3

Pairs of chromosomes (one from each parent) with the same genes in the same order, but possibly different alleles.

Question 4

How many homologous chromosomes do humans have?

Answer 4

Humans have 23 pairs = 46 total chromosomes.

Question 5

How many homologous chromosomes do fruit flies have?

Answer 5

Fruit flies have 4 pairs = 8 total chromosomes.

Question 6

What is crossing over?

Answer 6

Exchange of DNA between homologous chromosomes.

Question 7

When does crossing over occur?

Answer 7

During Prophase I of meiosis.

Question 8

What is the ultimate effect of crossing over?

Answer 8

Increases genetic diversity in gametes.

Question 9

How many male gametes are formed from one spermatocyte in meiosis?

Answer 9

Four sperm cells are formed.

Question 10

How many female gametes are formed from one oocyte?

Answer 10

One egg cell is formed.

Question 11

How many polar bodies are created from one oocyte?

Answer 11

Three polar bodies are created.

Question 12

What is the only immortal cell humans have?

Answer 12

The only immortal cells are Germ cells.

Question 13

How do we differentiate males from females based on gamete type?

Answer 13

• Males produce small, motile gametes (sperm or pollen)
• Females produce large, non-motile gametes (eggs or ovules)

Question 14

How many autosomes do humans have?

Answer 14

44 autosomes (22 pairs).

Question 15

What are the two sex chromosomes in humans?

Answer 15

X and Y chromosomes.

Question 16

What are bird sex chromosomes?

Answer 16

Birds have ZW and ZZ chromosomes.

Question 17

What is a karyotype?

Answer 17

A visual representation of chromosomes arranged in pairs by size and shape.

Question 18

What are the steps to create a karyotype for a human?

Answer 18

• Collect dividing cells.
• Arrest in metaphase using chemicals.
• Stain and photograph chromosomes.
• Arrange into homologous pairs.

Question 19

What type of disorders can karyotypes be used to diagnose?

Answer 19

• Down syndrome
• Turner syndrome
• Klinefelter syndrome

Question 20

How many chromosomes do all non-human primates have?

Answer 20

Non-human primates have 48 chromosomes.

Question 21

Why do humans have 2 fewer chromosomes than non-human primates?

Answer 21

Two ancestral chromosomes fused.

Question 22

What does a female calico cat tell us about the X chromosomes in a female?

Question 23

What is the key gene on the Y chromosome that is not found on the X chromosome?

Answer 23

The SRY gene triggers male sex determination.

Question 24

How does chromosome number determine sex in bees?

Answer 24

• Males are haploid (one set of chromosomes).
• Females are diploid (two sets of chromosomes).

Question 25

What determines sex in turtles?

Answer 25

The temperature determines sex in turtles.

Question 26

Who is the father of genetics?

Answer 26

Gregor Mendel.

Question 27

What organism did Gregor Mendel study?

Answer 27

He studied pea plants.

Question 28

What are some fun facts about Gregor Mendel?

Answer 28

He was a priest.

Question 29

What are the male parts of a flower?

Answer 29

The stamen, which is made of the anther and filament.

Question 30

What are the female parts of a flower?

Answer 30

The stigma, the style, and the ovary.

Question 31

What enlarges into a fruit?

Answer 31

The ovary of the flower enlarges into a fruit.

Question 32

What do we call a fertilized egg that develops inside the fruit?

Answer 32

A seed.

Question 33

What are the three types of plants that came before flowering plants?

Answer 33

* Mosses (Non-vascular plants) * Ferns (Vascular plants, non-seed) * Gymnosperms

Question 34

What is Mendel’s first law?

Answer 34

The Law of Segregation: Each individual has two alleles for each gene, and these alleles separate during gamete formation.

Question 35

What experiment did Mendel do that no one else thought to do?

Answer 35

Mendel cross-pollinated F1 generation plants (which were all hybrid) and observed the results in the F2 generation.

Question 36

What is the famous phenotype ratio observed in the offspring when two heterozygous individuals are crossed for one trait?

Answer 36

The 3:1 ratio in the F2 generation.

Question 37

What is Mendel’s second law?

Answer 37

The Law of Independent Assortment: Genes for different traits are inherited independently during gamete formation.

Question 38

What is the famous phenotype ratio observed in the offspring when crossing two heterozygous individuals for two traits?

Answer 38

The 9:3:3:1 ratio.

Question 39

How many different ways can 23 pairs of chromosomes assort?

Answer 39

8,388,608 possible combinations of chromosomes.

Question 40

What is nondisjunction?

Answer 40

Nondisjunction occurs when chromosomes fail to separate properly during meiosis.

Question 41

What condition does nondisjunction of chromosome 21 cause?

Answer 41

Down syndrome.

Question 42

What is an allele?

Answer 42

An allele is a variant form of a gene.

Question 43

How many alleles do you have for one gene?

Answer 43

You have 2 per gene.

Question 44

Distinguish between dominant and recessive genes.

Answer 44

* Dominant gene: Expresses its trait even when only one allele is present. * Recessive gene: Only expresses its trait when two copies are present.

Question 45

Distinguish between homozygous and heterozygous.

Answer 45

* Homozygous: Two identical alleles for a gene. * Heterozygous: Two different alleles for a gene.

Question 46

Distinguish between 1N/2N, diploid/haploid/polyploid.

Answer 46

* 1N is haploid (one set of chromosomes). * 2N is diploid (two sets of chromosomes). * Polyploidy is more than 2 sets of chromosomes.

Question 47

What is the phenotype ratio for a monohybrid cross?

Answer 47

3:1.

Question 48

What is the phenotype ratio for a dihybrid cross?

Answer 48

9:3:3:1.

Question 49

What is the phenotype ratio for a trihybrid cross?

Answer 49

27:9:9:9:3:3:1.

Question 50

Why are males at a disadvantage for genes on the X chromosome?

Answer 50

Males only have one X chromosome.

Question 51

What sex-linked condition was spread through the Houses of Europe that originated with Queen Victoria of England?

Answer 51

Hemophilia.

Question 52

What would we call Queen Victoria regarding her hemophilia allele?

Answer 52

The Queen was a carrier.

Question 53

What are the three alleles in the population for blood type?

Answer 53

* A * B * O

Question 54

How many possible gametes are there for a dihybrid cross?

Answer 54

4 gametes.

Question 55

How many possible gametes are there for a trihybrid cross?

Answer 55

8 gametes.

Question 56

Distinguish codominance from incomplete dominance in terms of phenotypes.

Answer 56

* Codominance: Both alleles are fully expressed. * Incomplete dominance: The heterozygote shows an intermediate phenotype.

Question 57

By what type of selection has teosinte changed into modern corn?

Answer 57

Artificial selection.

Question 58

What is pleiotropy?

Answer 58

Pleiotropy occurs when one gene influences multiple, seemingly unrelated traits.

Question 59

Give an example of pleiotropy.

Answer 59

Sickle cell disease.

Question 60

What is polygenic inheritance?

Answer 60

Polygenic inheritance involves multiple genes contributing to a trait.

Question 61

Give an example of polygenic inheritance.

Answer 61

Skin color.

Question 62

How many genes code for skin color?

Answer 62

6 genes.

Question 63

How many genes code for eye color?

Answer 63

2 genes.

Question 64

What does epistasis mean?

Answer 64

Epistasis is when one gene influences the expression of another gene.

Question 65

Give an example of epistasis.

Answer 65

Coat color in dogs.

Question 66

What is an example of how the environment can override genetics in an organism's phenotype?

Answer 66

Hydrangea flower color can change based on soil pH.

Question 67

What is a pedigree?

Answer 67

A family tree showing inheritance patterns of traits.

Question 68

How do you distinguish male and female in a pedigree?

Answer 68

* Squares are male. * Circles are female.

Question 69

How do you represent marriage and children in a pedigree?

Answer 69

* Horizontal lines for marriage. * Vertical lines for children.